Beginner with a foundation problem.

[herrbeckley]

Dear Forum,

Firstly, thank you for putting together such a thoughtful site.

I have just poured a 54" x 52" foundation slab. How I did this is an absolute mystery. I have worked with this sort of thing before, and yet for some truly stupid reason I cut off 20" in both directions. In your opinions, is is even possible to built an oven on such a foundation that would have an interior diameter of no less than 36"?

Secondly, is there anyone out there who has built an oven with a very aggressive dome in the style of the neapolitan commercial ovens?

Very Respectfully,

Tom

[dmun]

Re: Beginner with a foundation problem.

There's no reason why you can't cantelever out the support slab beyond the base. You could even justify doing so, by saying that the main weight of the oven is toward the center of the slab, rather than at it's edges.

There's been a lot of discussion of low dome neapollitan ovens here. You may want to use the search function at the top of each page. The general consensus seems to be that they need some reinforcement or buttressing at the sides to be structurally sound.

[james]

Re: Beginner with a foundation problem.

Welcome aboard Tom,

You have a lot of fun ahead of you.

Here are the rough dimensions I get:

Width
36" oven floor
9" oven walls (4 1/2" half bricks, thin exterior mortar)
6" all blanket insulation (3" per side)
2" Igloo stucco enclosure

53" Wide

Depth

36" floor
9" dome
3" rear insulation
1" rear stucco
8" vent landing (floor)

57" deep

It seems really tight depth wise. You can minimize your landing, but I've done that in the past, and you wil miss having a good size landing.

Can you made you slab bigger?

If you decide to that (while you are at it) and if you have the space, I would add enough wide to accommodate a 39" oven. 3" doesn't matter in your outdoor kitchen space, but I think you will enjoy having the space once you start cooking.

As Mel Brooks says, "work, work, work."

Check postings from johnrbek -- he built an aggressively low dome (though I don't think he brought the vent back directly oven the dome -- something we don't think is worth the extra effort).

I think there are a couple of other really low dome. Can anyone help with that?

James

[james]

Re: Beginner with a foundation problem.

Hi David,

We posted at the same time.

Of course you can cantilever the oven hearth slab. Duh.

Tom, I would take advantage of that to ge the oven size you want.

Another senior moment,
James

[james]

Re: Beginner with a foundation problem.

There's been a lot of discussion of low dome neapollitan ovens here. You may want to use the search function at the top of each page. The general consensus seems to be that they need some reinforcement or buttressing at the sides to be structurally sound.

There is a photo floating around that shows a low dome, where lateral thrust has pushed the vertical oven walls outward, and a brick in the more vertical section of the dome has fallen in.

Here is a photo of the professional building a low dome oven for a pizzeria in Sorrento. Note how tall the first course is. This builder shapes and fires his own bricks -- talk about dedication.

James

[Dutchoven]

Re: Beginner with a foundation problem.

Cantilevering the hearth slab will look really neat. Stability of the soldier course will be the main concern when springing an aggressively low dome. Can be done though, could harness it somehow or buttress it in a few places.
Good luck and we'll be here to help!
Dutch

[herrbeckley]

Re: Beginner with a foundation problem.

I am so close to understanding. You all are saying that I can suspend part of the hearth slab beyond the dimensions of the base. But the force of the oven dome is directed into the base through the dome walls, into the soldiers, which would be on or close to just above the overhang. Can the concrete support such distribution? Also, I should point out that I was initially planning on building a round base. Since construction has not begun I am going to do whatever you folks say. But I thought that I would create a round masonry base, then fill it in with concrete block and reinforced concrete. Then pour a hearth slab on that.

I realize I sound like a little crazy in this thread, but I really and open to learning all that I can in order to make this happen. I lived in Italy for five great years and I have dreamed for the last three (since getting back to the states) of building this oven.

TB

[james]

Re: Beginner with a foundation problem.

Tom,

The weight of the oven dome and floor are at least 4" inside the outer edge of the enclosure (the space of the insulation and enclosure walls), so the oven will basically rest on the part of the hearth that sits directly on the block stand. Which is good.

I think the round base is cool -- and you will see many of them in the FB Forum. Also, take a look at FB Photos -- where there are hundreds of oven photos.

Brick Pizza Oven Photos | Pizza Oven Photos | Pizza Photos

Hope this makes sense.

Where were you in Italy? We were in Florence for three years, and would still be there -- except that our older daughter was ready for high school. Oh well; I guess she had to grow up, and we're happy with the new school. :-)

James

[herrbeckley]

Re: Beginner with a foundation problem.

Thanks again for all the help. More explanation of cantilever is welcome. Just how would I do that on a round base?

James, I lived in Frascati, just south of Rome. There are several very fine bread ovens in that town making some of the finest pizza bianca and pane casareccia to be found. Over there they fire the ovens with long bundles of pruned branches from local trees, which I'm certain must prove very efficient. Many a morning I wandered over to Forno Ceralli to watch the bread bakers finish their shift. I would be there too if I could, but the service and family brought me back. Torno subito.

TB

[james]

Re: Beginner with a foundation problem.

Tom,

Excellent. Our producer of the Casa, Premio and Ristorante precast ovens is just down the road from you in Frascati. You probably ate in more than one pizzeria that uses their ovens. :-)

Build a form to support the concrete that hangs over the stand, use a flexible material such as thin plywood to shape the circle, and make sure that your rebar reaches over the stand to support the cantilever.

James

[SpringJim]

Re: Beginner with a foundation problem.

Thanks again for all the help. More explanation of cantilever is welcome. Just how would I do that on a round base?



TB

Don't overcomplicate it. The size of your base is?? You extend the hearth slab out beyond that base by the size you need. Use temporary support for your pour and I assume the reinforcing will exetend appropriately into all the cantilevered portion(s).

I was thinking recently about a mushroom oven. Drill a center caisson into the soil, pour a single reinforced column and then do a round oven base with interconnected reinforcing. Just like major columns used in highrise buildings. As long as you don't fly an airplane into the column, I think it would stand the test of time. (and no, no magic mushrooms for that one) We have some large diameter augers at work and drilling equipment....I've drilled a lot of holes!

[Dutchoven]

Re: Beginner with a foundation problem.

Tom,

Build a form to support the concrete that hangs over the stand, use a flexible material such as thin plywood to shape the circle, and make sure that your rebar reaches over the stand to support the cantilever.

James

One additonal way of reinforcing the edge is to bend a piece of rebar around the outer edge and tie it to those that go across the block walls into the middle of the slab, similar to a bond beam. reinforced concrete should have no trouble holding your oven even if it were to stick outside of the block walls. That type of construction really would only be unstable if they extended out more than half the width of the area that was supported which would be in the area of 24 inches or so in your case. I think you will be pleased with the way it will look in the end. You should do a search on a place called "Falling Water" it is a house that Frank Lloyd Wright designed and there were many cantilevered concrete slabs that made the owner nervous but they are still there and are still structurally sound.
All the best!
Dutch

[james]

Re: Beginner with a foundation problem.

One additonal way of reinforcing the edge is to bend a piece of rebar around the outer edge and tie it to those that go across the block walls into the middle of the slab, similar to a bond beam. reinforced concrete should have no trouble holding your oven even if it were to stick outside of the block walls.
Dutch

Excellent advice.
James

[dmun]

Re: Beginner with a foundation problem.

Want an easy way to make a round base? The huge round reinforced concrete drain tiles for culverts even have holes in them for branch line intersections. When they replace them for road widening projects, they often break the old ones up and truck them away at great expense. I bet a few phone calls could get you a chipped or used one for free.

[herrbeckley]

Re: Beginner with a foundation problem.

All of this is extremely helpful. I hope to check in after this weekend and offer an update as to my progress. Thanks to everyone.

One last thing. I was looking at the website of Monterey Masonry and I was deeply impressed with both the shape and material use in the construction of that dome. My only questions would be, (and I know that there is a big discussion about this topic) how hot do you think that oven can possibly get for cooking pizza seeing as how he uses red brick and lime mortar? Also, the double layer of red brick is intriguing. Would this not do a better job of retaining heat than the normal cladding and insulation?



TB